Videx VideoTerm Installation & Operation Manual

The Videx VideoTerm was the dominant 80-column card for the Apple II and II+, introduced in 1980 and manufactured in Corvallis, Oregon. It was the card that made the Apple II viable as a business machine — without it, WordStar, VisiCalc in wide-column mode, and the CP/M software ecosystem were all inaccessible. Apple’s own 80-column card didn’t arrive until the IIe in 1983.

At the heart of the VideoTerm is the Motorola MC6845 CRT Controller, a programmable CRTC that handles horizontal and vertical timing, cursor generation, and address calculation entirely in hardware. The VideoTerm exposes all 18 addressable MC6845 registers through a two-register I/O interface at the slot’s device select space, giving software complete control over display geometry, cursor shape, and timing parameters.

What This Manual Covers

This is the complete factory installation and operation manual, 154 pages. Key sections include:

• Hardware installation — slot selection, switch configuration, auxiliary connector wiring
• MC6845 register reference — all 18 control registers with bit-level descriptions, valid ranges, and timing formulas. This is the primary programming reference for software driving the card directly.
• Memory map — the 2KB character ROM, the 2KB display RAM, and the I/O register layout within the slot’s address space
• Firmware listing — annotated 6502 assembly for the on-card ROM, including the slot-3 IN#/PR# dispatch, 80-column firmware entry points, and the Pascal auxiliary slot protocol
• Character sets — complete character ROM tables for the standard and alternate character sets, including the inverse/flashing mode encoding
• Software examples — BASIC and assembly language examples for initializing the card, writing to the 80-column display, and reading back the cursor position
• CP/M integration — configuring the VideoTerm as the system console under Apple CP/M, including the terminal emulation parameters

Relationship to Site Articles

The A2FPGA series articles on this site document emulating the VideoTerm on an FPGA:

• Part 1: The Card That Made the Apple II Serious — hardware architecture, MC6845 internals, why slot 3 is architecturally special
• Part 2: Building the Rendering Pipeline — VRAM banking, C8-space ownership, the Pascal boot hang

The manual’s MC6845 register table (Section 3) and firmware listing (Section 6) were the primary references for the FPGA implementation. The Pascal auxiliary slot protocol described in Section 5 explains the exact handshake that caused the boot hang documented in Part 2.